As much as I want to agree with you, the people who like TikTok make up a significant amount of the population, and their opinions do matter--arguably more than yours, due to sheer numbers.
Smugly dismissing them doesn't do you any favors except for making you feel good about yourself for a few seconds.
You’d be surprised how many people don’t give a shit about TikTok. It’s just another blip in history like Facebook, Instagram, Vine, MySpace and others before them.
You say that like the typical 18 year old has any idea what they're doing when it comes to proper encryption and communication safety. That is never going to be the case.
It's a communication channel attached to the most popular social network for young people. Obviously they're going to use it a lot. They use it for the extreme convenience.